1. Field of the Invention
This application relates to handheld electronic devices and, more particularly, to a keyboard for a handheld electronic device having a first set of keys structured to engage two contacts and a second set of keys structured to engage a single contact and wherein each key in said first set of keys and said second set of keys is related to two indicia.
2. Background Information
Numerous types of handheld electronic devices are known. Examples of such handheld electronic devices include, for instance, personal data assistants (PDAs), handheld computers, two-way pagers, cellular telephones, and the like. Such handheld electronic devices are generally intended to be portable and thus must be relatively small. Since handheld electronic devices typically are portable, it is also desired that the form factor of the devices be sufficiently small and ergonomic that they can conveniently be transported with a belt clip, in a user's pocket, manually, or in a briefcase. Advancements in technology have permitted the form factor of such handheld electronic devices to be reduced while increasing their versatility and functionality, such as by increasing the number of functions provided by the device as well as increasing the number of software applications and the variety of their features. However, as the form factor of a handheld electronic device decreases and the number of functions provided by the device increases, the device potentially can become awkward and difficult to use. Thus, it is also desirable to improve the usability of a handheld electronic device as its form factor is reduced and its versatility is increased. Previous attempts to increase such usability have had limitations.
One such type of solution has involved the use of large numbers of keys which, when pressed in various combinations, would produce various functions. For instance, adjacent keys were depressed simultaneously to provide additional functions. In mobile electronics, keys oftentimes are operatively connected with metal domes that act as switches for the keys and that are collapsible and provide tactile feedback to a user when the domes are collapsed from a relaxed position to a deflected position. Due to the closeness of the keys, accidental simultaneous pressing of multiple keys oftentimes results in the collapsing of multiple domes, which can result in a confusing and/or undesirable tactile feedback to a user. Other attempts at improving usability have involved decreasing the quantity of keys on a handheld device while increasing the number of functions each key is to serve. Such systems potentially can become cumbersome because the various functions of a given key may additionally require the pressing of an additional key, such as, but not limited to, the SHIFT key or ALT key. In such a circumstance, the required multiple key pushing requires multiple hand movements which interfere with user friendliness.
It is also desirable to provide users with keys disposed in a common pattern. For example, an English language keyboard typically has the QWERTY layout. Thus, handheld electronic devices having a QWERTY keyboard with a reduced number of keys have been created. Such devices typically have more that one letter associated with most keys. For example, a single key on the QWERTY keyboard with a reduced number of keys would represent both the letter “A” and the letter “S”. Thus, the handheld electronic device needed to provide a means for selecting which letter the user intended to select when the key was depressed. An early differentiating means simply had the user depressing the key once for one letter and twice for the other letter. Alternatively, as described above, a combination of keys could be associated with one letter and not the other. That is, for example, the key by itself was associated with the letter “A” and the key plus the ALT key was associated with the letter “S.” The disadvantage to these means is that users of a QWERTY keyboard prefer to type in a traditional manner, i.e., without having to depress an extra key.
One means of addressing this disadvantage was provided by software. Disambiguation routines were created that suggested one of the letters based on, for example, a subsequent keystroke. That is, if the user had selected the letters “QU” and the next key depressed was the “A/S” key, the software would suggest the use of the letter “A” because the letter combination “QU” is almost always followed by a vowel. Such software solution would typically provide the user with a list of the less preferred letter combinations which the user could select if desired. This means was further improved by providing three conductors, a primary, secondary and tertiary conductor, under each key and which were operable with the software. The primary conductor was engaged when the key was depressed. The secondary and tertiary conductors were disposed adjacent to opposing lateral sides of the keys and were alternately closed when the user depressed one side of the key or the other. Thus, where the letter “A” was located on the left side of a single key, and the secondary conductor was located under the left lateral side of the key, when a user depressed the “A/S” key and pressed on the left side of the key, the primary conductor was engaged indicating the key had been depressed and, if the secondary conductor was depressed, the software would weigh, that is favor, the letter “A” over the letter “S”.
This solution, however, has disadvantages as well. For example, some keys may only be associated with a single letter thereby making the secondary and tertiary conductors redundant. Also, some keys, such as a “Z/X” key have letters that are so relatively uncommon in use that the software could reliably choose the proper letter the user intended to use. Again, the secondary and tertiary conductors were essentially wasted. Additionally, where each key was structured to overlay three conductors, all keys were elongated resulting in a wider keypad.